Rapid preparative isolation of erythrocentaurin from Enicostemma littorale by medium‐pressure liquid chromatography,its estimation by high‐pressure thin‐layer chromatography,and its α‐amylase inhibitory activity

Erythrocentaurin is a relatively simple natural product present among the members of Gentianaceae. A preparative method for the isolation of erythrocentaurin from the ethyl acetate fraction of Enicostemma littorale using medium‐pressure liquid chromatography has been reported. The method consisted of a simple step gradient from 10 to 20% ethyl acetate in n‐hexane. Using a 70 × 460 mm Si60 column, this method is capable of processing 20 g of material in <3 h (purity ≈ 97%). The recovery of erythrocentaurin was 87.77%. Estimation of erythrocentaurin in extracts and fractions based on high‐pressure thin‐layer chromatography was carried out on silica gel 60 F₂₅₄ plates with toluene/ethyl acetate/formic acid (80:18:2 v/v/v) as the mobile phase. The densitometric analysis was performed at 230 nm. A well‐separated compact band of erythrocentaurin appeared at R_f 0.54 ± 0.04. The analytical method showed good linearity in the concentration range of 200–1500 ng/band with a correlation coefficient of 0.99417. The limits of detection and quantification were found to be ≈60 and ≈180 ng/band, respectively. Erythrocentaurin exhibited a concentration‐dependent α‐amylase inhibition (IC₅₀ 1.67 ± 0.28 mg/mL). The outcome of the study should be considered for pharmacokinetic and biotransformation studies involving E. littorale.     

Luciferin‐Regenerating Enzyme Mediates Firefly Luciferase Activation Through Direct Effects of D‐Cysteine on Luciferase Structure and Activity

Luciferin‐regenerating enzyme (LRE) contributes to in vitro recycling of D‐luciferin. In this study, reinvestigation of the luciferase‐based LRE assay is reported. Here, using quick change site‐directed mutagenesis seven T‐LRE (Lampyris turkestanicusLRE) mutants were constructed and the most functional mutant of T‐LRE (T⁶⁹R) was selected for this research and the effects of D‐ and L‐cysteine on T⁶⁹R T‐LRE‐luciferase‐coupled assay are examined. Our results demonstrate that bioluminescent signal of T⁶⁹R T‐LRE‐luciferase‐coupled assay increases and then reach equilibrium state in the presence of 5 mm D‐cysteine. In addition, results reveal that 5 mm D‐ and L‐cysteine in the absence of T⁶⁹R T‐LRE cause a significant increase in bioluminescence intensity of luciferase over a long time as well as decrease in decay rate. Based on activity measurements, far‐UV CD analysis, ANS fluorescence and DLS (Dynamic light scattering) results, D‐cysteine increases the activity of luciferase due to weak redox potential, antiaggregatory effects, induction of changes in conformational structure and kinetics properties. In conclusion, in spite of previous reports on the effect of LRE on luciferase bioluminescent intensity, the majority of increase in luciferase light output and time‐course originate from the direct effects of D‐cysteine on structure and activity of firefly luciferase.     

Synthesis,Chemical Characterization,DNA Interaction and Antioxidant,Studies of New Nitrosubstituted Thioureas and Their Copper Complexes

In the present work new nitro substituted thioureas, and their copper complexes have been synthesized and characterized by FTIR and multinuclear NMR techniques. Some of the compounds namely 1‐benzoyl‐3‐(4‐chloro‐3‐nitrophenyl) thiourea (A‐1), 1‐benzoyl‐3‐(4‐chloro‐3‐nitrophenyl) thiourea (A‐2) and 1‐benzoyl‐3‐(2‐methoxy‐4‐nitrophenyl) thiourea (A‐2) have also been characterized by single crystal XRD. All the synthesized compounds have been screened for DNA binding potencies (using cyclic voltametry, UV‐vis spectroscopy) and free radical scavanging activities.     

Efficient photoelectrodes from anatase TiO2 nanotube arrays decorated with particles/rods/3D microflower rutile crystals for photoelectrochemical water splitting

Journal of Solid State Electrochemistry - Efficient photoanodes are designed of vertically aligned anatase TiO2 nanotube arrays (anatase TNTAs) decorated with different shaped rutile TiO2...     

Comparative study between chloramine-T and iodogen to prepare radioiodinated etodolac for inflammation imaging

This study describes a fast and efficient method for radiolabeling of etodolac with iodine-125 [¹²⁵I], where both chloramine-T and iodogen were used as oxidizing agents. The labeling reaction was carried out via electrophilic substitution of hydrogen atom with the iodonium cation I⁺. The labeling yield was found to be influenced by different factors such as drug concentration, pH of the reaction mixtures, different oxidizing agents, reaction time, temperature and different organic media. The radiochemical yield (RCY) was determined by TLC system using methylene chloride:ethyl acetate (3:7 v/v) as a developing solvent and by electrophoresis using cellulose acetate moistened with 0.02 M phosphate buffer pH 7. The maximum radiochemical yield of [¹²⁵I]Etodolac (87.7%) was obtained. Labeled etodolac shows a good localization in inflamed muscle. It excretes mainly via kidney and to some via liver.     

Microviscoelasticity of soft repulsive sphere dispersions: tracer particle microrheology of triblock copolymer micellar liquids and soft crystals

Tracer particle microrheology using diffusing wave spectroscopy-based microrheology is demonstrated to be a useful method to study the dynamics of aqueous Pluronic? F108 solutions, which are viewed as solutions of repulsive soft spheres. The measured zero-shear microviscosity of noncrystallizing micellar dispersions indicates micelle corona dehydration upon increasing temperature. Colloidal sphere thermal motion is shown to be exquisitely sensitive to the onset of crystallization in these micellar dispersions. High temperature dynamics are dominated by an apparent soft repulsive micelle-micelle interaction potential indicating the important role played by lubrication forces and ultimately micelle corona interpenetration and compression at sufficiently high concentrations. The measured microscopic viscoelastic storage and loss moduli are qualitatively similar to those experimentally observed in mechanical measurements on colloidal dispersions and crystals, and calculated from mode coupling theory of colloidal suspensions. The observation of subdiffusive colloidal sphere thermal motion at short time-scales is strong evidence that the observed microscopic viscoelastic properties reflect the dynamics of individual micelles rather than a dispersion of micellar crystallites.     

Two new acridone alkaloids from Glycosmis macrantha

Extraction and chromatographic separation of the extracts of dried stem barks of Glycosmis macrantha lead to isolation of two new acridone alkaloids, macranthanine and 7-hydroxynoracronycine, and a known acridone, atalaphyllidine. The structures of these alkaloids were determined by detailed spectral analysis and also by comparison with reported data.     

Urease inhibition and anti-leishmanial assay of substituted benzoylguanidines and their copper(II) complexes

A series of N,N',N'-trisubstituted guanidines (1-6) and their copper(II) complexes, [κ(2)(O,N)-C(6)H(5)CONHC(NHC(6)H(4)Cl)NR](2)Cu(ii) (R = iso-propyl (1a), n-butyl (2a), sec-butyl (3a), tert-butyl (4a), benzyl (5a), and para-tolyl (6a)) were synthesized and characterized using elemental analysis, FTIR and NMR spectroscopy. DFT studies were used to assess the location of the protons in the free ligands. However, calculations have shown that, in all cases, hydrogen bonding from either N-H group gives conformations that are very similar in energy. Single crystal XRD studies were used to characterize ligands 1 and 4 and the related complexes 1a and 4a. The structures reveal that these complexes are mononuclear in the solid state and that copper adopts a regular square planar geometry. In both metallic species, the N, N', N'-trisubstituted guanidine ligands chelate the Cu(II) atom using the oxygen and one nitrogen. The synthesized compounds were investigated for urease inhibition using thiourea as a standard drug. Most complexes exhibit a better activity than the respective guanidines and compound 1a was found to be the most active with IC(50) = 9.83 ± 0.07 μM (the IC(50) for thiourea is 21.0 ± 0.1 μM). The species were also screened for their anti-leishmanial activity. However, all of the compounds were devoid of any significant activity.     

Parametric aggregation in ordered weighted averaging

Incorporating further information into the ordered weighted averaging (OWA) operator weights is investigated in this paper. We first prove that for a constant orness the minimax disparity model [13] has unique optimal solution while the modified minimax disparity model [16] has alternative optimal OWA weights. Multiple optimal solutions in modified minimax disparity model provide us opportunity to define a parametric aggregation OWA which gives flexibility to decision makers in the process of aggregation and selecting the best alternative. Finally, the usefulness of the proposed parametric aggregation method is illustrated with an application in metasearch engine.